Integrated circuits (ICs) are typically housed within a plastic or ceramic package. The packages have leads or surface pads that are soldered to a printed circuit board. The circuit board and package are often located within an enclosed computer chassis that contains other circuitry associated with the computer system such as peripherals, memory cards, video cards, power supplies, etc..
It is desirable to have a high rate of heat transfer from the IC package in order to maintain the junction temperatures of the IC within safe operating limits. Modern microprocessors typically employ millions of transistors in internal circuitry that require some type of cooling mechanism, otherwise, excessive junction temperatures may affect the performance of the circuit and cause permanent degradation of the device. Hence, as the performance of integrated circuits continue to expand, the need to provide more efficient, reliable and cost effective heat removal methods has become increasingly important in the design of computer system enclosures and particularly in small general purpose computer systems, such as laptop and notebook computers. There also exists a need to remove heat from high-power profile components located within other small form factor or thin profile electronic devices.
High heat dissipating components located within the small confines of some consumer electronic devices may create "hot spots" at certain locations along the external casing of the device. These hot spots may be uncomfortable to the touch and, in some cases, may cause injury. Therefore, it is desirable to dissipate heat away from high heat generating components located within the enclosure of small form factor devices in such a way as to keep the internal components within their specified operating temperature range and to preclude the creation of hot spots along the exterior of the enclosure.
A number of prior art methods have been used to remove heat from heat generating components located within the confines of a computer system enclosure. For example, the method of cooling integrated circuit devices within notebook computers has evolved from the simple attachment of a finned heat sink to the top surface of the device, to the development of finned heat sinks having integral fans. More recent developments have include the use of large, flat heat spreading plates. In such applications, the integrated circuit (generally, the CPU) is directly or indirectly attached to a metal plate having a large thermal mass and a large heat transfer surface area. In some instances, the integrated circuit is thermally coupled to the heat spreading plate by a heat pipe or other low resistance thermal path. More recently, forced cooling air has been used to cool one side of a heat spreading plate having an integrated circuit attached to the other side. Although these heat transfer methods have proved sufficient in the past, they do not provide the heat removal capacity and/or efficiency needed to cool current and future high-performance microprocessors in portable general-purpose computers and other thin profile electronic devices.
What is needed then is an apparatus and method which solves the aforementioned problems associated with cooling internal electronic circuits located within portable consumer electronic and computer devices. Particularly, what is needed is a highly efficient cooling system that is conformable to the size and power consumption restrictions imposed by small form factor and thin profile electronic devices, such as, for example, notebook computers.